A question to Atheists and intelligent Guys?

Question

I believe in Evolution as one too many evidences support the idea.

But I want to ask you a question.
See if a donkey and a horse mate they can produce a mule.
Same is with a tiger and a female lioness (tigon)

So if humans have branched off from apes,
then why is it that humans cant mate with apes to produce you know(half ape half human species) what are the biological reasons?

Answer 1

>> See if a donkey and a horse mate they can produce a mule.

Right, but mules cannot reproduce - most are sterile.

>> Same is with a tiger and a female lioness (tigon)

Again, males are sterile.

>> what are the biological reasons?

Difference in chromosomes. We all used to have 48 chromosomes (24 from mom, 24 from dad) - but humans have 46 (23 from mom, and 23 from dad).

At some point in our direct evolutionary past, a pair of our chromosomes *fused*!

Chromosomes typically have 1 centromere ( http://en.wikipedia.org/wiki/Chromosome ) and end points of 2 telomeres ( http://en.wikipedia.org/wiki/Telomere ). But! Chromsome #2 has *2* centromeres! How did that happen?? It was the result of the fusion of two head-to-head chromosomes. The precise fusion site was at base #114,455,823 214,455,838.
The centromere corresponds to chimp chromosome #13.

See Ken Miller explain this process in crystal clarity:
http://www.youtube.com/watch?v=Gs1zeWWIm5M

----

So, I respond to the theist: why did God make it look like we have a fused chromosome if evolution is wrong?

Answer 2

The divergence of horses and donkey appears to have taken place 2-4 million years ago. Lions and tigers diverged in the last million years. The only experiments, performed in the Soviet Union, did not use chimps which diverged from humans 4-5 million years ago. The apes used were more distantly related. For ethical reasons (would a half-human have rights?), these experiments are not being performed.

Fertiile female tigons have been documented.

Answer 3

I think the persona above me may be right, who really wants to test that theory.

I am no atheist, defiantly no geneticist, but here is an idea.

It could also be that maybe the two species of big cats, or the horse and donkey are just close enough time wise and genetically wise that they can reproduce. For example Dogs of different breeds can reproduce with fertile offspring because their genetics only go back to recent history (relatively speaking), while horses and donkeys went their separate ways a few millennium ago and still have some genetic similarities. While Humans have had millions of years of separation that we are no longer compatible.

But one thing that should be noted both sets of offspring are infertile, they can't breed, it is a dead end.

all that being said however, back in the 80s the aquarium on Oahu Hawaii had a cross bred dolphin/whale. So if they were able to Breed to animals so far apart genetically, it may very well be possible to breed apes and man.

But again,who really wants to do that?

Answer 4

Humans and apes have a common ancestor. They didn't "branch off from apes."

To answer your question simply: Because there is no reason they should be able to.

Technically all creatures are decended from a common ancestor. The evidence we have clearly shows that after a certain (relitivly minimal) amount of change occurs, two ancestors can no longer mate. It's actually far more common than not. So the real question here is why anyone would think they should be able to mate.

Answer 5

I'm not a biologist but I do understand the basic concept. Just because two animals came from the same evolutionary root or branch, it does not mean they can inter-breed. Some can and some can't. I would suspect the ones that can are the very small minority. It has to do with the number of chromosomes they have and probably some other factors. Also it is a fact that when two of these types of animals do interbreed their offspring is sterile or a neuter so it can't continue to breed. One other note about your question: humans and apes both branched off from an ape-like ancestor millions of years ago.

Answer 6

I applaud you for seeking answers from both atheists and theists.

I believe the tiger/lion offspring is called a "Liger"?

There was an alleged humanzee awhile ago that walked upright and was smarter than the average chimp. He also looked a little like a cross between human and chimp. I think they finally used DNA testing to prove that he was 100% chimp though. I'm not sure that it's ever been proven one way or the other that human/ape crosses are impossible.

Answer 7

Horses and donkeys, if they mate, do indeed produce a mule. However, the overwhelming majority of mules are sterile (I think my AP Biology teacher many years ago said 1 in 1000 at MOST is fertile).

Lions and tigers have not split/diverged much at all genetically.

Humans and the other non-human apes, however, have a striking difference in our genome -- We have 46 chromosomes, they have 48. One of our pairs (one of our 23 pairs) is in fact the fusion of two of their pairs (one of their 24 pairs). This is sufficient genetic difference for us to be incompatible as breeding partners.

However... if you'd like to experimentally test this... you might want to learn sign language so you can ask first. ;) I remember Robin Williams once got hit on by a female gorilla when she saw how hairy he was (at least, according to the apocryphal stories I've heard from multiple sources... might just be a legend though).

*halo*

And from a purely asthetic view, I much prefer ligers to tigons.

Answer 8

The answer is that the environmental pressures on humans and primates have been greater than those that acted on tigers, lions etc (who in fact diverged before the apes) so the adaptation they have undergone is so great that micro-evolution has become macro-evolution. Man and primates are classified as totally different species but there is a grey area in the classification of the big cats because they have not diverged as far in evolutionary terms.

Answer 9

Special molecules called receptors on the surface of the sperm and egg of apes and humans vary to the point that it is impossible for them to connect properly, i.e. fertilization isn't possible. But if fertilization did somehow occur, the differences between the egg and sperm would halt the process of reproductive division. Although chimpanzees are primates and are 99% genetically similar to humans in both coding and non-coding regions (apparently our closest animal match) -- they have 24 pair of chromosomes and humans have only 23 pair. This difference in number of chromosomes would make normal cell division impossible during meiosis.

Answer 10

You may be looking at it upside down.

Humans are not more highly evolved apes.

Apes are more highly evolved humans.

They don't pollute the planet or go half way around the world to kill thousands of their kind like we do.

As for the mateing part, what self respecting ape would want to take the chance at polluting their gene pool with the obviously mentally inferior human genes.

Love and blessings Don